The chosen one
Mustaf is a variant of the Arabic name Mustafa, which is one of the titles of the Prophet Muhammad. It signifies someone who has been selected or preferred above others. While Mustafa is more common, Mustaf is a streamlined variation used in several Muslim-majority regions.
Less common today
Mustaf isn't in the latest US Top 1000. It last peaked at #7,434 in 2016.
US births per 5-year period, 1990βpresent (SSA data).